1. Field of the Invention
The invention relates to a vacuum cleaner nozzle which includes a first nozzle part having brush elements facing the floor and a second nozzle part which is movably arranged with respect to the first nozzle part and which has at least one suction opening through which air flows into an outlet tube which is connected to the nozzle.
2. Description of the Related Art
Nozzles of the type mentioned above are commonly known and comprise generally complicated mechanisms for facilitating relative movement between the two nozzle parts and for locking the two parts with respect to each other. When such a nozzle is used on a hard floor it rests on the brush elements, which consist of comparatively stiff bristles, whereas the second part, which forms an inlet part for air and which is made of comparatively hard material, is elevated or maintained above the floor. When such a nozzle is used on soft carpet, the nozzle parts are locked in such a position that the second part of the nozzle with the suction opening rests on the floor. Thus, during use on soft carpet, the brush elements are elevated or maintained above the floor and do not prevent or impede movement of the nozzle on the surface of the carpet.
It is known to use so-called automatic nozzles, as shown by DE 1628474. In automatic nozzles, the brush elements are supported by diaphragms or membranes which are under the influence of one or more springs and the sub-atmospheric pressure prevailing in the outlet tube. When the nozzle is placed or used on a hard floor, the outer portions of the brush elements abut the floor, which means that the central hard part of the nozzle forming the air inlet part is maintained above the floor so that air can flow through the brush elements and into the suction opening of the inlet part. A limited sub-atmospheric pressure prevails in the space above the membranes, but this pressure cannot overcome the spring force. The membranes, and hence the brush elements, remain in their lower position. When the nozzle is used on soft carpet, the brush elements and the supporting wheels on the inlet part and, hence, the complete nozzle will sink down into the carpet. This reduces air flow through the suction opening and increases the sub-atmospheric pressure above the membrane so that the spring force is overcome and the brush elements are lifted up from the surface of the carpet, thereby causing the inlet part to rest directly on the floor.
There also are nozzles in which the functions mentioned above have been integrated or combined so that it is possible to make a choice between using the nozzle as an automatic nozzle or as a nozzle which is manually operated.
A disadvantage with known automatic nozzles is that they are provided with a diaphragm of rubber or plastic which is relatively expensive and complicates the design of the nozzle. Therefore, there exists a need in the art for an automatic nozzle which is simple and inexpensive.